1. Field of the Invention
The present invention relates to a hollow blow-molded article and a material for the molded article.
2. Description of Related Art
In recent years, a method of producing ducts in the engine room as automobile components by hollow blow molding has become popular, and currently, polyamide-based materials have been mainly used. However, because the heat resistance of polyamide-based materials is unsatisfactory, materials for hollow blow molding which exhibit high heat resistance as well as chemical resistance and impact resistance have been required.
On the other hand, polyarylene sulfide resins (hereinafter, referred to as PAS resins) are engineering plastics with excellent heat resistance, chemical resistance, flame retardancy, electrical characteristics, and the like, and there are growing demands for their applications such as electric and electronic parts, automobile parts and precision machinery parts.
Although various attempts have been conventionally made to use materials for hollow blow molding which employ PAS resins, because the PAS resins exhibit a very high melt fluidity when molded, in the case of using a typical extrusion blow molding method (i.e., a method in which a parison is extruded and then blow molded), the degree of drawdown of the parison is very high, which makes it extremely difficult to be molded into a container with less uneven thickness. For this reason, the current situation is that the method has been limited to the injection molding method in most cases, and most of the molded articles of PPS resins is small and has not been much applied to large parts such as bottles and tanks through, for example, blow molding.
As an example of application of PAS resins to the blow molding process, a resin composition obtained by melting and kneading a PAS resin and an epoxy group-containing olefin-based copolymer has been known (Patent Document 1). However, although this PAS resin exhibited high melt viscosity, the proportion of the terminal carboxyl groups was high, and the PAS resin contained a large amount of low molecular weight components. Because of this, not only there is room for improvements in moldability of the composition in terms of the drawdown resistance and uneven thickness when carrying out a hollow blow molding process, but also there is room for improvements in mechanical strength, especially thermal shock resistance, because the proportion of reaction products between the low molecular weight components in the PAS resins and the epoxy group-containing olefin-based copolymers is increased. Accordingly, the use thereof in more severe environments, for example, around the automobile engine, has not been accomplished.
Patent Document 1: Japanese Unexamined Patent Application, First Publication No. Hei 3-236930